RMB no longer selects in edit mode
Not really sure what happened there, did you change any settings under the key map editor? You may have run into some sort of bug.

Did you uninstall prior to reinstalling? If reinstalling Blender did not solve the problem, then you may need to clear your Blender user preferences.
Not sure how the installer works, or if it deletes/overwrites user preferences on setup, I always use the "portable" standalone versions, but apparently something must have been left over from previous installation.

Try one of the following:


Either go to your user profile folder, should be located under C:\Users\User Name\AppData\Roaming\Blender Foundation\Blender\2.##\config and delete whatever content is there. Make sure you back up any relevant files before deleting if you have customized any Blender preferences or settings. Then Run Blender again


or 


Try and download one of the zipped Blender packages, unpack it anywhere in you system (say like the Desktop), then using the file explorer navigate to the extracted folder and under Blender\2.##\ create a new folder named "Config" so that it's path is Blender\2.##\Config and then try and run Blender from Blender\blender-app.exe